An X-ray imaging device that picks up an X-ray image with an imaging panel that includes a plurality of pixel portions is known. In such an X-ray imaging device, for example, projected X-rays are converted into charges by photodiodes. Converted charges are read out when thin film transistors (hereinafter also referred to as TFTs) are caused to operate, the TFTs being provided in the pixel portions. With the charges being read out in this way, an X-ray image is obtained. JP-A-2013-46043 discloses such an imaging panel. The photodiode in the configuration disclosed in JP-A-2013-46043 has a PIN structure in which an n-type semiconductor layer, an i-type semiconductor layer, and a p-type semiconductor layer are laminated. On the photodiode, an upper electrode formed with a transparent conductive film is provided; and under the photodiode, a lower electrode containing a metal such as aluminum is provided. The upper electrode is connected with a common electrode line for supplying a bias voltage.